Electric heater



FIG. 1 is a perspective view of an electric heater showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is a bottom plan view thereof; and

FIG. 6 is a left side elevation view thereof, the opposite side being a mirror image of that shown. 

The ornamental design for an electric heater, as shown and described. 